Synergistic fuel composition for enhancing fuel cold flow properties

ABSTRACT

Disclosed herein is a fuel oil composition describing a synergistic blend of petroleum based fuels with renewable fuels to enhance the combined fuel&#39;s cold temperature operability properties. The oil composition comprises a petroleum based component and a renewable fuel component.

FIELD OF THE INVENTION

This invention relates generally to fuel oil compositions. The inventionmore specifically relates to synergistic blends of petroleum based fuelswith renewable fuels and methods of using such compositions to enhancethe cold temperature operability properties of fuels.

BACKGROUND OF THE INVENTION

Globally there is a significant desire to utilize “green” or “renewablefuels” as a source of energy. These fuels are gaining popularity due tovarious social and political factors. The effect of petroleum fuels oncarbon dioxide emissions/global warming and the dependence on foreignsources of fuel are a few of the prominent factors driving popularsupport,

Renewable fuels are gaining greater market acceptance as a cutter stockto extend petroleum diesel market capacity. The blends of renewablefuels with petroleum diesel are being used as a fuel for diesel engines,utilized for heating, power generation, and for locomotion with ships,boats, as well as motor vehicles.

The renewable cutter stock portion of a blended fuel is commonly knownas bio-diesel. Bio-diesel is defined as fatty acid alkyl esters ofvegetable or animal oils. Common oils used in bio-diesel production arerapeseed, soya, palm tallow, sunflower, and used cooking oil or animalfats.

Bio-diesel is prepared by reacting whole oils with alcohols (mainlymethanol) in the presence of a catalyst (acid or base), usually sodiumhydroxide. This method of preparing bio-diesel, known as the CD process,is described in numerous patent applications (see, DE-A 4 209 779, U.S.Pat. No. 5,354,878, EP-A-56 25 04, the entire teachings of which areincorporated herein by reference).

Bio-diesel is a legally registered fuel and fuel additive with the U.S.Environmental Protection Agency (EPA). In order for a material toqualify as a bio-diesel, the material fuel must meet ASTM D-6751-03 (theentire teaching of which is incorporated herein by reference)specifications independent of the oil or fat used or the specificprocess employed to produce the additive. The ASTM D-6751 specificationis intended to insure the quality of bio-diesel to be used as a blendstock for 20% and lower blend levels.

Although bio-diesel has many positive political and environmentalattributes, it also has certain negative characteristics which must betaken into consideration when utilizing the material as an alternativefuel or as a blend stock for petroleum diesel.

It is well known that bio-derived fuels are inherently more sensitive tocold weather operations as compared to typical petroleum derived fuels.These fuels generally have poor handling properties as exhibited bytheir elevated temperatures for pour point (point at which the fuel isun-pumpable) and the relatively high Cold Filter Plugging Point (CFPP,temperature at which the material will plug fuel filters).

The inherent cold temperature sensitivity can be attributed to theabundance of linear saturated hydrocarbons (paraffin's) in the renewablefuel as compared to petroleum based fuels.

Petroleum based fuels must also meet certain handling and userequirements as described in ASTM D 975 (the entire teaching of which isincorporated herein by reference). These fuels must be pumpable and mustnot plug fuel filters at temperatures of use. Thus, the cold flowattributes of the fuel is a critical property which must be monitoredand controlled if the product is to be considered to be fit for purpose.

In order to meet emissions and fuel efficiency goals, automotiveOriginal Equipment Manufacturers (OEM's) are investigating the use ofNOx traps, particulate traps and direct injection technologies. Suchtraps and catalyst systems tend to be intolerant to sulfur, this coupledwith the demonstrated adverse environmental consequences of burningsulfur rich fuels has resulted in a global effort to reduce the sulfurcontent of fuels (Reference World-Wide Fuel Charter, April 2000, Issuedby ACEA, Alliance of Automobile Manufacturers, the entire teaching ofwhich is incorporated herein by reference). These low sulfur andultra-low sulfur fuels are becoming increasingly necessary to ensurecompliance with emissions requirements over the full useful life of thelatest technological generation of vehicles. Governments are alsointroducing further legislation for the reduction in particulate matterand fuel emissions.

In the United States, the Environmental Protection Agency (EPA)regulations require that the sulfur content of on road fuel meet theUltra Low Sulfur specification, specifically less than 15 ppm by mass ofsulfur in the finished fuel. Similar regulations are also in placeglobally.

The method most commonly utilized to reduce the sulfur content of fuelsis referred to as “hydro-treating”. Hydro-treating is a process by whichhydrogen, under pressure, in the presence of a catalyst, reacts withsulfur compounds in the fuel to form hydrogen sulfide gas and ahydrocarbon. However, hydro-treating to reduce sulfur content resultsnot only in the removal of sulfur from the fuel but also dramaticallyaffects the chemical composition and physical properties of petroleumfuels.

Hydro-treated fuels generally have a higher paraffin content and loweraromatic content. The increased n-paraffin's can affect the temperatureand amount of crystals coming out of solution at diminishedtemperatures. These changes in fuel composition dramatically impact thecold flow properties of the fuel. The paraffins can form lamellarcrystals when the temperature is lowered and in some cases agglomerateto inhibit fuel flow, Generally, the cold temperature handling and usecharacteristics hydro-treated (ULS Ultra Low Sulfur) fuels are inferiorto Low Sulfur (LS) fuels.

The changes in petroleum fuel composition can be further compounded bythe inclusion of renewable fuels as a blending stock for petroleumfuels. It is generally believed that the blending of modern ULS fuelswith poor cold flow properties and renewable based fuels with evenpoorer cold flow characteristics will have a great detrimental effect onbulk fuel cold flow properties.

Problems associated with a diminished Cold Temperature Operabilitycharacteristic such as deteriorated fluidity at low temperature (i.e.,increased pour point and/or cold filter plugging point) are a greatconcern to the fuel industry. It is anticipated, therefore, that manydifficulties associated with engines, such as clogging of fuel passagesor fuel filters, may occur in a normal temperature range at which theengine is operated in certain climate regions.

The present invention addresses the Cold Temperature Operabilityconcerns of the fuel industry. Specifically, the invention discloses anovel composition having an unexpected synergy between petroleum fueland renewable fuels, as well as the use of renewable fuel petroleum fuelblends to substantially enhance fuel of the cold flow properties.Additionally, methods are disclosed by which these compositions can beutilized.

BRIEF SUMMARY OF THE INVENTION

The present invention relates generally to fuel oil compositions. Theinvention more specifically relates to synergistic blends of petroleumbased fuels with renewable fuels and methods of using such compositionsto enhance the Cold Temperature Operability properties of fuels.

The instant invention describes compositions and methods for thepreparation and use of fuel compositions with dramatically enhanced ColdTemperature Operability characteristics. The blended fuel compositionscomprise (i) a petroleum based component and (ii) a renewable component.

Another aspect of the invention as described herein is the use ofadditives such as (a) low temperature operability/cold flow additives,(b) corrosion inhibitors, (c) cetane improvers, (d) detergents, (e)lubricity improvers, (f) dyes and markers, (g) anti-icing additives, (h)demulsifiers/anti-haze additives, (i) antioxidants, (j) metaldeactivators, (k) biocides, and (l) thermal stabilizers (m) antifoamsand (n) static dissipater additives, in combination with a blended fuelcomposition of the instant invention in order to enhance other fuelproperties.

Another embodiment is directed toward a method for synergisticallyenhancing the cold temperature operability of a fuel by employing asuitable combination of a petroleum based component and a renewablebased component.

Another embodiment of the present invention is directed toward a methodfor operating an internal combustion engine such as acompression-ignition engine using as fuel for the engine a suitablepetroleum based component and a suitable renewable based component,wherein the combination synergistically enhances cold temperatureoperability of said fuel.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates generally to fuel oil compositions. Theinvention more specifically relates to one or more synergistic blends ofpetroleum based fuels with renewable fuels and methods of using suchcompositions to enhance the cold temperature operability properties offuels.

The instant invention is directed to fuel compositions, comprising (i) apetroleum based component and (ii) a renewable based component wherein asynergistic combination of these fuel components dramatically enhancesthe Cold Temperature Operability of the fuel blend composition.

Cold Temperature Operability (CTO) of fuel is a measure of the inherenthandling and use characteristics of a fuel at diminished temperatures.

A given fuel's CTO characteristics is generally considered as the lowesttemperature at which the fuel can be utilized without causingoperational difficulties. A fuel's CTO is estimated by its cloud point,pour point and it's CFPP. In Canada another method Low Temperature FlowTest (LTFT) is also employed.

The cloud point (CP) or wax appearance temperature (WAT) of a fuel isthe point at which first visible crystals are detected in the fuel.Cloud point can be evaluated using ASTM D-2500/D-5771/D 5772/D-5773(visible method), the entire teaching of which is incorporated herein byreference, and by IP-389 (crystal formation method), the entire teachingof which is incorporated herein by reference.

The pour point (PP) is a standardized term for the temperature at whichan oil, for example, mineral oil, diesel fuel or hydraulic oil, stopsflowing upon cooling. Pour point of petroleum fuels can be evaluatedusing ASTM D-97 (the entire teaching of which is incorporated herein byreference) and ISO-3016 (the entire teaching of which is incorporatedherein by reference).

The Cold Temperature Filter Plugging Point (CFPP) of a fuel is thetemperature at and below which wax in the fuel will cause severerestrictions to flow through a filter screen. CFPP is believed tocorrelate well with vehicle operability at lower temperatures.

CFPP of petroleum fuels in evaluated using ASTM D-6371 (the entireteaching of which is incorporated herein by reference), IP-309 (theentire teaching of which is incorporated herein by reference), andEN-116 (the entire teaching of which is incorporated herein byreference).

Low Temperature Flow Test (LTFT) is very similar in principle andfunction to CFPP and is evaluated using ASTM D-4539 (the entire teachingof which is incorporated herein by reference).

Synergy as defined in the present invention is the enhancement in ColdTemperature Operability characteristics of a fuel achieved by theblending of two or more fuel components which results in a blend withsuperior cold flow properties as compared to each individual componentof the blend additively.

The synergism between the fuel components is generally evaluated byblending the renewable fuel with the petroleum fuel and measuring theCFPP response of the blends as compared to the blend fuel components

In the present embodiment, the petroleum based component is ahydrocarbon derived from refining petroleum or as a product ofFischer-Tropsch processes (well known to those skilled in the art). Thehydrocarbon may also be a solvent. The fuel products are commonlyreferred to as petroleum distillate fuels.

Petroleum Distillate Fuels encompass a range of distillate fuel types.These distillate fuels are used in a variety of applications, includingautomotive diesel engines and in non on-road applications under bothvarying and relatively constant speed and load conditions.

Petroleum distillate fuel oils can comprise atmospheric or vacuumdistillates. The distillate fuel can comprise cracked gas oil or a blendof any proportion of straight run or thermally or catalytically crackeddistillates. The distillate fuel in many cases can be subjected tofurther processing such hydrogen-treatment or other processes to improvefuel properties. The material can be described as a gasoline or middledistillate fuel oil.

Gasoline is a low boiling mixture of aliphatic, oleinic, and aromatichydrocarbons, and optionally, alcohols or other oxygenated components.Typically, the mixture boils in the range from about room temperature upto about 225° C.

Middle distillates can be utilized as a fuel for locomotion in motorvehicles, air planes, ships and boats as burner fuel in home heating andpower generation and as fuel in multi purpose stationary diesel engines.

Engine fuel oils and burner fuel oils generally have flash pointsgreater than 38° C. Middle distillate fuels are higher boiling mixturesof aliphatic, olefinic, and aromatic hydrocarbons and other polar andnon-polar compounds having a boiling point up to about 350° C. Middledistillate fuels generally include, but are not limited to, kerosene,jet fuels, and various diesel fuels. Diesel fuels encompass Grades No.1-Diesel, 2-Diesel, 4-Diesel Grades (light and heavy), Grade 5 (lightand heavy), and Grade 6 residual fuels. Middle distillatesspecifications are described in ASTM D-975, for automotive applications(the entire teaching of which is incorporated herein by reference), andASTM D-396, for burner applications (the entire teaching of which isincorporated herein by reference).

Middle distillates fuels for aviation are designated by such terms asJP-4, JP-5, JP-7, JP-8, Jet A, Jet A-1. JP-4 and JP-5. The Jet fuels aredefined by U.S. military specification MIL-T-5624-N, the entire teachingof which is incorporated herein by reference, and JP-8 is defined byU.S. Military Specification MIL-T83133-D, the entire teaching of whichis incorporated herein by reference. Jet A, Jet A-1 and Jet B aredefined by ASTM specification D-1655 and Def. Stan. 91, the entireteachings of which are incorporated herein by reference.

The different fuels described (engine fuels, burner fuels and aviationfuels) each have further to their specification requirements (ASTMD-975, ASTM D-396 and D-1655, respectively) allowable sulfur contentlimitations. These limitations are generally on the order of up to 15ppm of sulfur for On-Road fuels, up to 500 ppm of sulfer for Off-Roadapplications and up to 3000 ppm of sulfur for Aviation fuels.

In the present embodiment, a renewable based component is an organicmaterial that is derived from a natural; replenishable feed stock whichcan be utilized as source of energy. Suitable examples of a renewablecomponent include, but are not limited to, bio-diesel, ethanol, andbio-mass. Other renewable materials are well known to those skilled inthe art.

In the present embodiment, “bio-diesel” refers to all mono-alkyl estersof long chain fatty acids derived from vegetable oils or animal fats.

Bio-diesel is commonly produced by the reaction of whole oils withalcohols in the presence of a suitable catalyst. Whole oils are naturaltriglycerides derived from plant or animal sources. The reaction ofwhole oil with an alcohol to produce a fatty acid ester and glycerin iscommonly referred to as trans esterification. Alternatively, bio-dieselcan be produced by the reaction of a fatty acid with an alcohol to formthe fatty acid ester.

The fatty acid segments of triglycerides are typically composed ofC₁₀-C₂₄ fatty acids, where the fatty acid composition can be uniform ora mixture of various chain lengths. The bio-diesel according to theinvention may comprise single feed sourced components, or blends ofmultiple feed stocks derived from vegetable(s), or animal(s) origin. Thecommonly used single or combination feed stocks include, but are notlimited to, coconut, corn, castor, linseed, olive, palm, peanut,rapeseed, safflower, sunflower, soybean, tall oil, tallow, lard, yellowgrease, sardine, menhaden, herring and used cooking oils and fats.

Suitable alcohols used in either of the esterification processes can bealiphatic or aromatic, saturated or unsaturated, branched or linear,primary, secondary or tertiary, and may possess any hydrocarbon chainhaving lengths from about C-1 to about C-22. The industry and typicalchoice being identified as methanol.

Rio-diesel composition is established by specification parameters setforth in ASTM D-6751, the entire teaching of which is incorporatedherein by reference. The fatty acid ester must meet and maintain theestablished specification parameters set forth in ASTM D-6751,regardless of the whole oil feed source or the process utilized for itsproduction.

The ASTM4D-6751 specification outlines the requirements for bio-diesel(B100) to be considered as a suitable blending stock for hydrocarbonfuels.

During the research and development efforts to evaluate cold temperatureoperability properties of petroleum fuels, renewable fuels and theirblends, it was discovered that a combination of petroleum fuels withrenewable fuels resulted in an enhancement of the cold temperatureoperability of the final blended fuel

This discovery is in opposition to the commonly held belief in thepetroleum industry that blending petroleum fuels with renewable fuelswill have a detrimental effect on the overall cold temperatureoperability characteristics of the fuel. The unexpected synergisticeffect described herein had heretofore been unknown in the petroleumfuel or renewable fuel industries.

The synergistic effect on Cold Temperature Operability can be achievedby blending a renewable fuel with a petroleum fuel. The renewable fueland petroleum fuels can be blended in any proportion necessary whereinthe final blend is appropriate to be utilized as a fuel.

The fuel can contain about 100% renewable components, however, in thescope of the invention, the renewable content of the blend is typicallyup to about 50% by volume of the finished fuel blend, more typically upto about 35% by volume of the finished fuel blend, and alternatively upto about 20% by volume of the finished fuel blend.

The invention can be practiced at high renewable fuel concentrations,wherein the renewable fuel content is greater than about 15% by volumeof the finished fuel blend. The invention is also applicable atrenewable fuel concentrations as low as about 15, 12.5, 12, 11, and 10%by volume of the finished fuel blend, and even at very low renewablefuel concentrations as low as about 7.5, 5, 3, 2, 1, and 0.5% by volumeof the finished fuel blend.

The magnitude of the positive effect on Cold Temperature Operability asindicated by CFPP of the blended fuel is dependant on not only thevolume % of renewable fuel used to make the fuel blend, but also on thespecific chemical composition and physical properties of the renewablefuel utilized in the blend.

While the general positive effect on CFPP exhibited by all renewablefuels is universal, the greatest positive effect on CFPP of the blendedfuel was seen where the renewable fuel utilized in the blend was derivedfrom rapeseed as the natural, replenishable feed stock.

The effect by rapeseed derived renewable fuel on blend fuel CFPP isattributed to the substantial amount of mono unsaturated fatty chains inthe rapeseed feedstock. The mono-unsaturated (eneoic—oleic type) fattychains are desirable to polyunsaturated fatty acid chains(dieneoic—linoleic, and trieneoic linolenic type) such as thoseprevalent in soy bean derived feed stocks, and desirable to saturated(stearic type) fatty acid chains as those found in tallow or palmderived feeds.

It is further considered as part of the invention the blending of thedescribed renewable feed stocks, and the utilization of these blendswith petroleum fuel to enhance cold temperature operabilitycharacteristics of the final blend.

An aspect of this invention is a method of synergistically enhancing theCold Temperature Operability of a fuel by metering into the petroleumfuel the missing synergistic renewable fuel component.

The invention described can be practiced by blending the renewable fuelwith the petroleum fuel or by Mending of two or more fuels where onepetroleum fuel contains the renewable fuel component.

Regardless of the order, location, or method of blending, there will beexhibited a synergistic enhancement of cold flow properties greater thanthat of each individual fuel.

It is additionally considered as part of the present invention theutilization of other additives in combination with the fuel blend, wherethese additives being present in such amounts so as to provide theirnormal intended functions

A non-exclusive list of additives typically used in petroleum fuel andwhich can be incorporated into petroleum fuel renewable fuel blends are.(a) low temperature operability/cold flow additives such asethylene-unsaturated ester copolymers, comb polymers containinghydrocarbyl groups pendant from a polymer backbone, polar nitrogencompounds having a cyclic ring system, hydrocarbyl, hydrocarbon polymerssuch as ethylene alpha-olefin copolymers polyoxyethylene esters, ethersand ester/ether mixtures such as behenic diesters of polyethyleneglycol, (b) corrosion inhibitors, such as fatty amines, poly amines andamides there of known as filming amines, and polymers of fatty acidsknown as dimmer trimer acids, (c) cetane improvers such as 2-ethyl hexylnitrite (2EHN) and di-tert butyl peroxide (DTBP), (d) detergents such ascomponents derived from reactions of organic acids with polyamine suchas ethylenediamine, diathylene triamine, triethylene tetramine andtetraethylene pentamine, (e) lubricity improvers, such as componentsderived from chemical families that include: long chain fatty acid,derivatives of such fatty acids to include salts (both mineral andorganic), amides and esters, dimers/trimers of fatty acids, and poly andalkyl amines (which are generally known as “filming amines”) and theirderivatives such as amides, salts, and oxyalkylates, (f) dyes andmarkers, (g) anti-icing additives such as ethylene glycol monomethylether or diethylene glycol monomethyl ether (h) demulsifiers/anti-hazeadditives such as those produced from a phenol and an aldehyde underacidic or basic polymerization condition (industrially known as resolesor novelacs) and their alkoxylated (ethylene, propylene or butyleneoxide) products, (i) antioxidant compounds such as hindered phenolsexemplified by 2,6-di-t-butyl-4-methyl phenol (BHT, butylated hydroxytoluene), 2-t-butyl-4-heptyl phenol, 2-t-butyl-4-octyl phenol,2-t-butyl-4-octyl phenol, 2-t-butyl-4-dodecyl phenol,2,6-di-t-butyl-4-heptyl phenol, 2,6-di-t-butyl-4-dodecyl phenol,2-methyl-6-di-t-butyl-4-heptyl phenol, and2-methyl-6-di-t-butyl-4-dodecy-1 phenol, ortho coupled phenols toinclude 2,2′-bis(6-t-butyl-4-heptyl phenol), 2,2′-bis(6-t-butyl-4-octylphenol), and 2,2′-bis(6-t-butyl-4-dodecyl phenol), where BHT issuitable, as are 2,6- and 2,4-di-t-butylphenol and 2,4,5- and2,4,6-triisopropylphenol for use in jet fuels, (j) metal deactivatorssuch as (1) benzotriazoles and derivatives thereof for example, 4- or5-alkylbenzotriazoles (e.g., tolutriazole) and derivatives thereof,4,5,6,7-tetrahyc benzotriazole and 5,5′-methylenebisbenzotriazole,Mannich bases of benzotriazole or tolutriazole, e.g.,1-[bis(2-ethylhexyl)aminomethyl]tolutriazole,1-[bis(2-ethylhexyl)aminomethyl]benzotriazole, andalkoxyalkylbenzotriazoles such as 1-(nonyloxymethyl)-benzotriazole,1-(1-butoxyethyl)benzotriazole and1-(1-cyclohexyloxybutyl)-tolutriazole, (2) 1,2,4-triazoles andderivatives thereof, for example, 3-alkyl(or aryl)-1,2,4-triazoles, andMannich bases of 1,2,4-triazoles, such as1-[bis(2-ethylhexyl)aminomethyl-1,2,4-triazole;alkoxyalkyl-1,2,4-triazoles such as 1-(1-butoxytheyl)-1,2,4-trizole, andacylated 3-amino-1,2,4-triazoles, (3) Imidazole derivatives, for example4,4′-methylenebis(2-undecyl-5-methylimidazole) andbis[(N-methyl)imidazol-2-yl]carbinol octyl ether (4) Sulfur-containingheterocyclie compounds, e.g., 2-mercaptobenzothiazole,2,5-dimercapto-1,3,4-thiadiazole and derivatives thereof, and3,5-bis[di(2-ethyl-hexyl)aminomethyl]-1,3,4-thiadiazolin-2-O-ne, and (5)Amino compounds and imino compounds, such as N,N′-disalicylidenepropylene diamine (DMD), salicylaminoguanadine and salts thereof, (k)biocides, (l) thermal stabilizers such as those compounds containingsecondary and tertiary amines, (in) anti-foams such as poly ethermodified siloxanes and (n) conductivity additives such as those havingcomponents derived from chemical families that include: aliphaticamines-fluorinated polyolefins (U.S. Pat. No. 3,652,238, the entireteaching of which is incorporated herein), chromium salts and aminephosphates (U.S. Pat. No. 3,758,283, the entire teaching of which isincorporated herein), alpha-olefin-sulfone copolymer class—polysulphoneand quaternary ammonium salt (U.S. Pat. No. 3,811,848, the entireteaching of which is incorporated herein), polysulphone and quaternaryammonium salt amine/epichlorhydrin adduct dinonylnaphthy]sulphonic acid(U.S. Pat. No. 3,917,466, the entire teaching of which is incorporatedherein), copolymer of an alkyl vinyl monomer and a cationic vinylmonomer (U.S. Pat. No. 5,672,183, the entire teaching of which isincorporated herein), alpha-olefin-maleic anhydride copolymer class(U.S. Pat. Nos. 3,677,725 & 4,416,668, the entire teachings of which areincorporated herein), methyl vinyl ether-maleic anhydride copolymers andamines (U.S. Pat. No. 3,578,421, the entire teaching of which isincorporated herein), alpha.-olefin-acrylonitrile (U.S. Pat. Nos.4,333,741 & 4,388,452, the entire teachings of which are incorporatedherein), alpha-olefin-acrylonitrile copolymers and polymeric polyamines(U.S. Pat. No. 4,259,087, the entire teaching of which is incorporatedherein), and copolymer of an alkylvinyl monomer and a cationic vinylmonomer and polysulfone (U.S. Pat. No. 6,391,070, the entire teaching ofwhich is incorporated herein), an ethoxylated quat (U.S. Pat. No.5,863,466, the entire teaching of which is incorporated herein),hydrocarbyl monoamine or hydrocarbyl-substituted polyalkylenieamine(U.S. Pat. No. 6,793,695, the entire teaching of which is incorporatedherein), acrylic-type ester-acrylonitrile copolymers and polymericpolyamines (U.S. Pat. Nos. 4,537,601 & 4,491,651, the entire teachingsof which are incorporated herein), diamine succinamide reacted with anadduct of a ketone and SO₂ (β-sutlone chemistry) (U.S. Pat. No.4,252,542, the entire teaching of which is incorporated herein).

Low temperature operability cold/flow additives are used in fuels toenable users and operators to handle the fuel at temperatures belowwhich the fuel would normally cause operational problems. Distillatefuels such as diesel fuels tend to exhibit reduced flow at lowtemperatures due in part to formation of waxy solids in the fuel. Thereduced flow of the distillate fuel affects transport and use of thedistillate fuels in refinery operations and internal combustion engine.This is a particular problem during the winter months and especially innorthern regions where the distillates are frequently exposed totemperatures at which solid formation begins to occur in the fuel,generally known as the cloud point (ASTM D 2500) or wax appearance point(ASTM D 3117). The formation of waxy solids in the fuel will in timeessentially prevent the ability of the fuel to flow, thus pluggingtransport lines such as refinery piping and engine fuel supply lines.Under low temperature conditions during consumption of the distillatefuel, as in a diesel engine, wax precipitation and gelation can causethe engine fuel filters to plug resulting in engine inoperability.Example of Low temperature operability/cold flow available from InnospecInc. of Newark, Delaware is PPD 8500.

Corrosion Inhibitors are a group of additives which are utilized toprevent or retard the detrimental interaction of fuel and materialspresent in the fuel with engine components. The additives used to impartcorrosion inhibition to fuels generally also function as lubricityimprovers. Examples of corrosion inhibitors available from Innospec Inc.of Newark, Del. are DCI 6A, and DCI 4A.

Cetane Improvers are used to improve the combustion properties of middledistillates. As discussed in U.S. Pat. No. 5,482,518 (the entireteaching of which is incorporated herein by reference) fuel ignition indiesel engines is achieved through the heat generated by aircompression, as a piston in the cylinder moves to reduce the cylindervolume during the compression stroke. In he engine, the air is firstcompressed, then the fuel is injected into the cylinder; as the fuelcontacts the heated air, it vaporizes and finally begins to burn as theself-ignition temperature is reached. Additional fuel is injected duringthe compression stroke and the fuel burns almost instantaneously, oncethe initial flame has been established. Thus, a period of time elapsesbetween the beginning of fuel injection and the appearance of a flame inthe cylinder. This period is commonly called “ignition delay” and mustbe relatively short in order to avoid “diesel knock”. A majorcontributing factor to diesel fuel performance and the avoidance of“diesel knock” is the cetane number of the diesel fuel. Diesel fuels ofhigher cetane number exhibit a shorter ignition delay than do dieselfuels of a lower cetane number. Therefore, higher cetane number dieselfuels are desirable to avoid diesel knock. Most diesel fuels possesscetane numbers in the range of about 40 to 55. A correlation betweenignition delay and cetane number has been reported in “How Do DieselFuel Ignition Improvers Work” Clothier, et al., Chem. Soc. Rev, 1993,pg. 101-108, the entire teaching of which is incorporated herein. Cetaneimprovers have been used for many years to improve the ignition qualityof diesel fuels. Example of a Cetane Improvers available from InnospecInc. of Newark, Del. is CI-0801.

Detergents are additives which can be added to hydrocarbon fuels toprevent or reduce deposit formation, or to remove or modify formeddeposits, It is commonly known that certain fuels have a propensity toform deposits which may cause fuel injectors to clog and affect fuelinjector spray patterns. The alteration of fuel spray patterns may causenon uniform distribution and/or incomplete atomization of fuel resultingin poor fuel combustion. The accumulation of deposits is characterizedby overall poor drivability including hard starting, stalls, roughengine idle and stumbles during acceleration. Furthermore if depositbuild up is allowed to proceed unchecked, irreparable harm may resultwhich may require replacement or non-routine maintenance. In extremecases, irregular combustion could cause hot spots on the pistons whichcan resulted in total engine failure requiring a complete engineoverhaul or replacement. Examples of detergents available from InnospecInc. of Newark, Del. are DDA 350, and OMA 580.

Lubricity improver 's increase the lubricity of the fuel, to preventwear on contacting metal surfaces in the engine. Certain diesel enginedesigns rely on fuel as a lubricant for their internal movingcomponents. A potential detrimental result of poor lubricating abilityof the fuel can be premature failure of engine components (e.g., fuelinjection pumps). Examples of lubricity improvers available fromInnospec Inc. of Newark, Del. are OLI 9070.x, and OLI 9101.x.

Dyes and Markers are materials used by the EPA (Environmental ProtectionAgency) and the IRS (Internal Revenue Service) to monitor and trackfuels. Since 1994 the principle use for dyes in fuel is attributed tothe federally mandated dying or marking of untaxed “off-road” middledistillate fuels as defined in the Code of Federal Regulations, Title26, Part 48.4082-1(26 CFR 48.4082-1). Dyes are also used in AviationGasoline; Red, Blue and Yellow dyes denote octane grade in Avgas.Markers are used to identify, trace or mark petroleum products withoutimparting visible color to the treated product. One of the mainapplications for markers in fuels is in Home Heating Oil. Examples ofDyes and Markers available from Innospec Inc. of Newark, Del. are OilRed B4 and Oil Color IAR.

Anti-Icing Additives are mainly used in the aviation industry and incold climates. They work by combining with any free water and loweringthe freeze point of the mixture that no ice crystals are formed.Examples of anti-icing additives available from Innospec Inc. of Newark,Del. are Dri-Tech and DEGME.

Demulifiers/Anti-Haze additives are mainly added to the fuel to combatcloudiness problems which maybe caused by the distribution of water in awet fuel by dispersant used in stability packages. Examples ofdemulsifiers/anti-haze additives available from Innospec Inc. of Newark,Del. are DDH 10 and DDH 20.

Antioxidants are used to inhibit the degradation of fuels by interactionof the fuel with atmospheric oxygen. This process is known as “OxidativeInstability”. The oxidation of the fuel results in the formation ofalcohols, aldehydes, ketones, carboxylic acids and further reactionproducts of these functional groups, some of which may yield polymers.Antioxidants function mainly by interrupting free radical chainreactions thus inhibiting peroxide formation and fuel degradation.Examples of antioxidants additives available from Innospec Inc. ofNewark, Del. are AO 37 and AO 29.

Metal Deactivators are chelating agents that form stable complexes withspecific metals. Certain metals (e.g., copper and zinc) are verydetrimental to fuel stability as they catalyze oxidation processesresulting in fuel degradation (increase in gums, polymers, color, andacidity). An example of metal deactivator available from Innospec Inc.of Newark, Del. is DMD.

Biocides are used to control microorganisms such as bacteria and fungi(yeasts, molds) which can contaminate fuels. Biological problems aregenerally a function of fuel system cleanliness, specifically waterremoval from tanks and low point in the system. An example of Biocideavailable from Innospec Inc. of Newark, Del. is 6500.

Thermal Stabilizers are additives which help prevent the degradation offuel upon exposure to elevated temperatures. Fuel during its use cycleis exposed to varying thermal stresses. These stresses are: 1) Instorage—where temperatures are low to moderate, 0 to 49° C. (32 to 120°F.), for long periods of time, 2) In vehicle fuel systems wheretemperatures are higher depending on ambient temperature and enginesystem, 60 to 70° C. (140 to 175° F.), but the fuel is subjected tothese higher temperatures for shorter periods of time than in normalstorage, and 3) In (or near) the engine—where temperatures reachtemperatures as high as 150° C. (302° F.) before injection or recycling,but for even shorter periods of time. Thermal stability additivesprotect the fuel uniformity/stability against these types of exposures.Examples of thermal stabilizers available from Innospec Inc. of Newark,Del. are FOA 3 and FOA 6.

Anti-foams additives are mainly utilized to prevent foaming of the fuelduring pumping, transport and use. Examples of anti-foams available inthe marketed are the TEGOPREN™ (available from Dow Corning), SAG™(available from ex OSi—now Dow), and RHODORSIL™ (available from ex RhonePoulene).

Canductvity Additives/Static Dissipaters/Electrical Conductivityadditives are used to minimize the risk of electrostatic ignition inhydrocarbons fuels and solvents. It is widely known that electrostaticcharges can be frictionally transferred between two dissimilar,nonconductive materials. When this occurs, the electrostatic charge thuscreated appears at the surfaces of the contacting materials. Themagnitude of the generated charge is dependent upon the nature of and,more particularly, the respective conductivity of each material.Electrostatic charging is known to occur when solvents and fuels flowthrough conduits with high surface area or through “fine” filters. Thepotential for electrostatic ignition and explosion is probably at itsgreatest during product handling, transfer and transportation. Thus, thesituations which are of greatest interest to the petroleum industry areconditions where charge is built up in or around flammable liquids, andthe possibility of discharge leading to incendiary sparking, and perhapsto a serious fire or explosion. Countermeasures designed to preventaccumulation of electrostatic charges on a container being filled suchas container grounding (i.e., “earthing”) and bonding are routinelyemployed. However, it has been recognized that grounding and bondingalone are insufficient to prevent electrostatic build-up in lowconductivity, volatile organic liquids. Organic liquids such asdistillate fuels like diesel, gasoline,jet fuel, turbine fuels andkerosene, and relatively contaminant free light hydrocarbon oils such asorganic solvents and cleaning fluids are inherently poor conductors.Static charge accumulates in these fluids because electric charge movesvery slowly through these liquids and can take a considerable time toreach a surface which is grounded. Until the charge is dissipated, ahigh surface-voltage potential can be achieved which can create anincendiary spark, resulting in an ignition or an explosion, Theincreased hazard presented by low conductivity organic liquids can beaddressed by the use of additives to increase the conductivity of therespective fluids. The increased conductivity of the liquid willsubstantially reduce the time necessary for any charges that exist inthe liquid to be conducted away by the grounded inside surface of thecontainer. Examples of conductivity additives available from Iospec Inc.of Newark, Del. are Stadis® 425, Stadis® 450.

The general chemistries and compositions of these additive familieswhich function to impart the desired fuel characteristics are fullyknown in the art. A person having ordinary skill in the art to whichthis invention pertains can readily select an additive to achieve theenhancement of the desired fuel property.

The invention is further described by the following illustrative butnon-Limiting examples. The following examples depict the synergisticenhancement of fuel cold temperature operability by the propercombination of a petroleum fuel and a renewable fuel.

EXAMPLE

Synergy Test Method: The effect on CFPP upon combining a petroleum fueland a renewable fuel was evaluated. The base line CFPP of a series ofpetroleum fuels, and renewable fuels available in the fuel market wereevaluated as per ASTM method D-6371. The results of the evaluation aredepicted in Table 1.

TABLE 1 Middle distillate and Renewable Feedstock's CFPP ° C. Diesel 1−9 Diesel 2 −34 Diesel 3 −13 Diesel 4 −4 BIO 001 Rape −18 BIO 002 Soy −3BIO 003 Palm 9 BIO 004 Rape −26 BIO 006 Tallow 3 BIO 007 Soy 2 BIO 008Soy −5 BIO 009 Tallow 3 BIO 010 Coconut −8 BIO 011 Used Cooking Oil 2BIO 012 Mixed Tank 71 3 BIO 013 Tallow 8 BIO 014 Rape −15 BIO 015Coconut, BD100 −8 BIO 016 Palm, BD200 11

The data indicates a wide range of CFPP performance characteristicsranging from −9° C. to −34° C. for petroleum fuels, and −26° C. to 11°C. for the renewable fuels.

These fuels were then mixed to prepare a B5 and B20 fuel blends. TheCFPP of the blended fuels were measured, and the resulting data comparedwith the CFPP of the base petroleum fuel. The results of the evaluationare depicted in Table 2.

TABLE 2 Blends % v/v FAME CFPP Change in CFPP Diesel 1 BIO 001 0 Rape −9Diesel 1 BIO 001 5 −17 −8 Diesel 1 BIO 001 20 −22 −13 Diesel 2 BIO 001 0Rape −34 Diesel 2 BIO 001 5 −43 −9 Diesel 2 BIO 001 20 −41 −7 Diesel 3BIO 001 0 Rape −13 Diesel 3 BIO 001 5 −23 −10 Diesel 3 BIO 001 20 −24−11 Diesel 4 BIO 001 0 Rape −4 Diesel 4 BIO 001 5 −16 −12 Diesel 4 BIO001 20 −20 −16 Diesel 1 BIO 002 0 Soy −9 Diesel 1 BIO 002 5 −9 0 Diesel1 BIO 002 20 −7 2 Diesel 2 BIO 002 0 Soy −34 Diesel 2 BIO 002 5 −40 −6Diesel 2 BIO 002 20 −28 6 Diesel 3 BIO 002 0 Soy −13 Diesel 3 BIO 002 5−13 0 Diesel 3 BIO 002 20 −11 2 Diesel 4 BIO 002 0 Soy −4 Diesel 4 BIO002 5 −7 −3 Diesel 4 BIO 002 20 −6 −2 Diesel 1 BIO 003 0 Palm −9 Diesel1 BIO 003 5 −11 −2 Diesel 1 BIO 003 20 −10 −1 Diesel 2 BIO 003 0 Palm−34 Diesel 2 BIO 003 5 −33 1 Diesel 2 BIO 003 20 −10 24 Diesel 3 BIO 0030 Palm −13 Diesel 3 BIO 003 5 −16 −3 Diesel 3 BIO 003 20 −13 0 Diesel 4BIO 003 0 Palm −4 Diesel 4 BIO 003 5 −10 −6 Diesel 4 BIO 003 20 −9 −5Diesel 4 BIO 004 0 Rape −4 Diesel 4 BIO 004 5 −10 −6 Diesel 4 BIO 004 20−15 −11 Diesel 4 BIO 006 0 Tallow −4 Diesel 4 BIO 006 5 −6 −2 Diesel 4BIO 006 20 −7 −3 Diesel 3 BIO 007 0 Soy −13 Diesel 3 BIO 007 5 −15 −2Diesel 3 BIO 007 20 −8 5 Diesel 4 BIO 007 0 Soy −4 Diesel 4 BIO 007 5 −6−2 Diesel 4 BIO 007 20 −5 −1 Diesel 3 BIO 008 0 Soy −13 Diesel 3 BIO 0085 −12 1 Diesel 3 BIO 008 20 −11 2 Diesel 4 BIO 008 0 Soy −4 Diesel 4 BIO008 5 −5 −1 Diesel 4 BIO 008 20 −17 −13 Diesel 4 BIO 009 0 Tallow −4Diesel 4 BIO 009 5 −5 −1 Diesel 4 BIO 009 20 −7 −3 Diesel 4 BIO 010 0Coconut −4 Diesel 4 BIO 010 5 −7 −3 Diesel 4 BIO 010 20 −3 1 Diesel 4BIO 011 0 Used −4 Diesel 4 BIO 011 5 Cooking Oil −6 −2 Diesel 4 BIO 01120 −8 −4 Diesel 4 BIO 012 0 Mixed Tank −4 Diesel 4 BIO 012 5 71 −6 −2Diesel 4 BIO 012 20 −9 −5 Diesel 4 BIO 013 0 Tallow −4 Diesel 4 BIO 0135 −7 −3 Diesel 4 BIO 013 20 −8 −4 Diesel 4 BIO 014 0 Rape −4 Diesel 4BIO 014 5 −8 −4 Diesel 4 BIO 014 20 −18 −14

Data clearly indicates that there is a positive influence on coldtemperature operability characteristics of a petroleum fuel by blendingthe fuel with a renewable fuel. At the B5 blend level, 79% of thepetroleum/renewable fuel blends had a CFPP enhancement of 2° C. or moreas compared to the base petroleum fuel, and at the B20 level, 58% of theblends exhibited 2° C. or more CFPP enhancement.

The greatest magnitude of effect was seen with Rapeseed based materialas the renewable fuel feed. The average CFPP enhancement by the Rapeseedmaterial at B5 blend level was 8.1° C., and at the B20 level was 12° C.

These results were a great surprise as the commonly held belief in thepetroleum industry is tat renewable fuelers will have a greatdetrimental effect on cold temperature operability characteristics ofpetroleum fuels. It is evident that by a proper choice of the type andvolume % of a renewable fuel, a fuel blend can be produced with enhancedCold Temperature Operability characteristics.

While certain embodiments of the present invention have been disclosedin detail, it is to be understood tat various modifications may beadopted without departing from the spirit of the invention or scope ofthe following claims.

1. A composition for enhancing cold temperature operability of a fuelcomprising a petroleum based component and a renewable based component.2. The composition of claim 1, wherein said petroleum based component isselected from the group consisting of a middle distillate fuel, a jetfuel, and a Fischer-Tropsch fuel.
 3. The composition of claim 1, whereinsaid petroleum based component comprises less then about 500 ppm by massof sulfur.
 4. The composition of claim 3, wherein said petroleum basedcomponent comprises less then about 15 ppm by mass of sulfur.
 5. Thecomposition of claim 1, wherein said renewable based component isselected from the group consisting of a product derived from the transesterification of naturally occurring whole oils of plants or animalswith an alcohol, the ester of a fatty acid derived from naturallyoccurring oils, and an alcohol.
 6. The composition of claim 5, whereinsaid natural oils are selected from the group consisting of Soy, Palm,Rapeseed, Linseed, Coconut, Corn, Cotton, Cooking, Sunflower, Safflower,Tallow, Lard, Yellow Grease, Fish Oils and blends thereof.
 7. A methodof synergistically enhancing cold temperature operability of a fuel,comprising employing a combination of a petroleum based component and arenewable based component.
 8. The method of claim 7, wherein saidpetroleum based component is selected from the group consisting of amiddle distillate fuel, a jet fuel, and a Fischer-Tropsch fuel.
 9. Themethod of claim 7, wherein said petroleum based component comprises lessthen about 500 ppm by mass of sulfur.
 10. The method of claim 9, whereinsaid Petroleum Based Component comprises less then about 15 ppm by massof sulfur.
 11. The method of claim 7, wherein said renewable basedcomponent selected from the group consisting of product derived from thetrans esterification of naturally occurring whole oils of plants oranimals with an alcohol, or the ester of a fatty acid derived fromnaturally occurring oils, and an alcohol.
 12. The method of claim 11,wherein said natural oils are selected from the group consisting of Soy,Palm, Rapeseed, Linseed, Coconut, Corn, Cotton, Cooking, Sunflower,Safflower, Tallow, Lard, Yellow Grease, Fish Oils, and blends thereof.13. The method of claim 12, wherein said natural oil is Rapeseed adblends thereof.
 14. The method of claim 12, wherein said natural oil isSoy and blends thereof.
 15. The method of claim 11, wherein said alcoholis selected from the group consisting of linear, branched, alkyl,aromatic, primary, secondary, tertiary, and polyols.
 16. The method ofclaim 7, wherein said renewable based component is present in the fuelblend between about 0.1% to about 99.9% v/v of fuel blend.
 17. Themethod of claim 16, wherein said renewable based component is present inthe fuel blend between about 1% to about 50% v/v of fuel blend.
 18. Themethod of claim 17, wherein said renewable based component is present inthe fuel blend between about 2% to about 25% v/v of fuel blend.
 19. Themethod of claim 1, wherein the synergistic fuel blend combination of afurther comprise one or more additives selected from the groupconsisting of: (a) low temperature operability/cold flow additives, (b)corrosion inhibitors, (c) cetane improvers, (d) detergents, (e)lubricity improvers, (f) dyes and markers, (g) anti-icing additives, (h)demulsifiers/anti haze additives, (i) antioxidants, (j) metaldeactivators, (k) biocides, (l) thermal stabilizers (m) antifoams, (n)static dissipater additives, and combinations thereof.
 20. A method foroperating an internal combustion engine such as a compression-ignitionengine using as fuel for the engine a petroleum based component and arenewable based component, wherein said combination synergisticallyenhances cold temperature operability of said fuel.